The systems for generating vehicle electricity, as known in the art, usually comprise an electric machine that is responsible for the electrical energy production, driven by an automotive engine at the ignition moment, through a synchronizing belt. The alternator feeds all electrical devices during the vehicle operation and recharges the battery, and its name is a reference to the type of produced current. It works according to the electromagnetic induction principle: the electric current flows through the rotor creating a magnetic field which induces the movement of electrons in the stator coils, resulting in an alternating current. As cars operate with direct current, the automotive alternators include two fundamental components: the rectifier plate (rectifier), which transforms the alternating current into direct current, as well as the voltage regulator, which controls the produced voltage.
However, and despite the broad use of these electric machines in vehicles, said electric machines contribute to fuel consumption and carbon dioxide (CO2) emissions, since these machines represent a mechanical energy consumer source from the crankshaft. As the engine mechanical energy is obtained from thermal energy generated from the fuel combustion, the alternator works as a load to the system, which, when the battery is in a loading situation, induces to fuel consumption increasing to compensate the energy used by the alternator. Moreover, even with an adequate battery charge level, the alternator continues to consume mechanical energy from the crankshaft due to its inertial mass which is still spinning at the same engine speed.
The fuel consumption and carbon dioxide emissions represent, in a direct form, indicators that determine the vehicle energy efficiency. The fuel burning, in particular the fossil fuel, produces high concentrations of carbon dioxide (CO2) generated from combustion. The high emissions levels of carbon dioxide expelled into the atmosphere promote detrimental effects to the environment, such as the greenhouse effect and consequent global warming, resulting in natural disasters possibilities (e.g. tsunami) as well as climate changes which influence agricultural production. Furthermore, the fuel consumption is related to the carbon monoxide (CO) and hydrocarbons (HC) emissions which are proven harmful to human health.
To minimize the negative effect of the alternators on the vehicle fuel consumption, it was designed and implemented some inventiveness and improvements. Typically, projects are based on increasing the alternator efficiency (electrical and mechanical) and the possibility of an alternator strategic operation as a function of the battery electricity demand.
The invention disclosed in document US 20090176608 uses a pulley to reduce the alternator belt tension, decreasing the impact during the coupling process. Therefore, the torsion spring and the clutch spring are wound in opposite directions, thus allowing the clutch spring to expand in order to couple with the inner surface during acceleration of the pulley relative to the cushion.
The system disclosed in document U.S. Pat. No. 5,139,463 uses an alternator with serpentine belt together with a spring in order to allow instantaneous rotation in the direction of the alternator pulley, allowing the alternator to perform instantaneous rotations in opposite directions.
The system disclosed in document U.S. Pat. No. 7,712,592 uses a limiter spring course for the alternator over-uncoupling. This uncoupling assembly is used to transfer the rotational movement between the engine shaft and the belt. The limiter spring course prevents contaminants from entering to the uncoupling assembly, retaining the lubricant within the assembly.
The system disclosed in document CN 1668859 uses bare wire spring and grease lubrication in the uncoupling alternator pulley. The torsion spring and the clutch spring are wound in opposite directions, thereby allowing the clutch spring to expand into coupling, adhering itself to the inner surface during the pulley acceleration relative to the cushion and uncoupling during the slowdown relative to the cushion pulley.
The system disclosed in document U.S. Pat. No. 6,870,350 uses a controller to measure voltage in the secondary winding. It is used for controlling magnetic field of synchronous machines and can withstand to parameter variations of the operating point, being insensitive to nonlinearities and adapting to the design changes.
However, despite all the described inventions reduce the effects of the alternator mechanical load on the crankshaft, no one of them allow the complete alternator mechanical uncoupling relative to the crankshaft.
The system disclosed in document U.S. Pat. No. 6,798,094 uses a rotating electric machine, and in particular, the vehicle alternator which comprises a stator resiliently mounted on a heat conductive resin. This inventiveness produces the radial mechanical uncoupling between the stator and the coating resin, so as to dissipate thermal energy from the stator towards the resin. This system heavily depends on improvement of heat dissipation properties and the entire system vibration.
In order to minimize the effect of the alternator mechanical load on the crankshaft, the documents DE 19638872 and U.S. Pat. No. 7,816,893, related to the Bosch LIN alternators line, use the strategy of, under specific conditions, electrically uncouple the alternator relative to the vehicle electrical loads. This electrical uncoupling occurs when the battery has sufficient charge level to powering the vehicle electrical system, or when the alternator operating conditions are inappropriate, among other situations. The electric coupling is carried out when the battery reaches a minimum level of electrical charge and needs to be recharged. Hence, during the periods of the alternator electrical uncoupling, the mechanical load on the crankshaft is minimized. However, part of the mechanical load still remains due to the rotating inertial mass present in the alternator shaft. Not only the rotor spinning consumes a portion of the energy produced by the combustion engine, but also the rotor spinning, relative to the stator, leads to generate a magnetic field and to appear an electric voltage (even with the alternator electrically uncoupled), without generating a useful electric energy production, i.e. work. This situation unnecessarily increases the energy consumption produced by the combustion engine. Therefore, even with lower intensity, the crankshaft continues with the effect of a mechanical load, impacting the internal combustion engine energetic efficiency.
Objects of the Invention
It is a first object of the present invention a system to perform the alternator selective coupling and uncoupling relative to the crankshaft, so as to reduce its load and the carbon dioxide (C02) emission level, and, therefore, the fuel consumption, in addition to other greenhouse gases emissions, such as carbon monoxide (CO), hydrocarbons (HC) and nitrogen oxides (NOX).
It is another object of the present invention a system to perform the alternator selective coupling and uncoupling from not simultaneous electrical and mechanical coupling/uncoupling.
It is an additional object of the present invention a system to perform the alternator selective coupling and uncoupling in order to overcome the known art.